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241 nips-2012-No-Regret Algorithms for Unconstrained Online Convex Optimization


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Author: Brendan Mcmahan, Matthew Streeter

Abstract: Some of the most compelling applications of online convex optimization, including online prediction and classification, are unconstrained: the natural feasible set is Rn . Existing algorithms fail to achieve sub-linear regret in this setting unless constraints on the comparator point ˚ are known in advance. We present algox rithms that, without such prior knowledge, offer near-optimal regret bounds with respect to any choice of ˚. In particular, regret with respect to ˚ = 0 is constant. x x We then prove lower bounds showing that our guarantees are near-optimal in this setting. 1


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